1 /* ISC license. */
2
3 /* MT-unsafe */
4
5 #include <skalibs/sysdeps.h>
6 #include <string.h>
7 #include <sys/stat.h>
8 #include <fcntl.h>
9 #include <sys/wait.h>
10 #include <unistd.h>
11 #include <errno.h>
12 #include <signal.h>
13
14 #ifdef SKALIBS_HASPOSIXSPAWN
15
16 #include <stdlib.h>
17 #include <spawn.h>
18 #include <skalibs/config.h>
19
20 #else
21
22 #include <skalibs/sig.h>
23 #include <skalibs/strerr2.h>
24 #include <skalibs/exec.h>
25
26 #endif
27
28 #include <skalibs/types.h>
29 #include <skalibs/allreadwrite.h>
30 #include <skalibs/env.h>
31 #include <skalibs/djbunix.h>
32
33 /*
34 If n = 0 : child's stdin and stdout are the same as the parent's
35 If n >= 1 : pipes between parent and child.
36 Parent reads on even ones, writes on odd ones.
37 */
38
child_spawn(char const * prog,char const * const * argv,char const * const * envp,int * fds,unsigned int n)39 pid_t child_spawn (char const *prog, char const *const *argv, char const *const *envp, int *fds, unsigned int n)
40 {
41 pid_t pid ;
42 #ifdef SKALIBS_HASPOSIXSPAWN
43 posix_spawn_file_actions_t actions ;
44 posix_spawnattr_t attr ;
45 int e ;
46 #else
47 int syncpipe[2] ;
48 #endif
49 int p[n ? n : 1][2] ;
50 size_t m = sizeof(SKALIBS_CHILD_SPAWN_FDS_ENVVAR) ;
51 unsigned int i = 0 ;
52 char modifs[m + 1 + n * UINT_FMT] ;
53 memcpy(modifs, SKALIBS_CHILD_SPAWN_FDS_ENVVAR "=", sizeof(SKALIBS_CHILD_SPAWN_FDS_ENVVAR)) ;
54 for (; i < n ; i++)
55 {
56 if (pipe(p[i]) < 0) goto errpi ;
57 if ((ndelay_on(p[i][i & 1]) < 0) || (coe(p[i][i & 1]) < 0))
58 {
59 i++ ; goto errpi ;
60 }
61 }
62 for (i = 2 ; i < n ; i++)
63 {
64 m += uint_fmt(modifs + m, p[i][!(i & 1)]) ;
65 if (i+1 < n) modifs[m++] = ',' ;
66 }
67 modifs[m++] = 0 ;
68
69 #ifdef SKALIBS_HASPOSIXSPAWN
70
71 e = posix_spawnattr_init(&attr) ;
72 if (e) goto erre ;
73 {
74 sigset_t set ;
75 sigemptyset(&set) ;
76 e = posix_spawnattr_setsigmask(&attr, &set) ;
77 if (e) goto errattr ;
78 e = posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGMASK) ;
79 if (e) goto errattr ;
80 }
81 e = posix_spawn_file_actions_init(&actions) ;
82 if (e) goto errattr ;
83 if (n >= 2 && p[1][0])
84 {
85 e = posix_spawn_file_actions_adddup2(&actions, p[1][0], 0) ;
86 if (e) goto erractions ;
87 e = posix_spawn_file_actions_addclose(&actions, p[1][0]) ;
88 if (e) goto erractions ;
89 }
90 if (n && p[0][1] != 1)
91 {
92 e = posix_spawn_file_actions_adddup2(&actions, p[0][1], 1) ;
93 if (e) goto erractions ;
94 e = posix_spawn_file_actions_addclose(&actions, p[0][1]) ;
95 if (e) goto erractions ;
96 }
97 {
98 int nopath = !getenv("PATH") ;
99 size_t envlen = env_len(envp) ;
100 char const *newenv[envlen + 2] ;
101 if (!env_mergen(newenv, envlen+2, envp, envlen, modifs, m, 1)) goto erractions ;
102 if (nopath && (setenv("PATH", SKALIBS_DEFAULTPATH, 0) < 0))
103 {
104 e = errno ; goto erractions ;
105 }
106 e = posix_spawnp(&pid, prog, &actions, &attr, (char *const *)argv, (char *const *)newenv) ;
107 if (nopath) unsetenv("PATH") ;
108 if (e) goto erractions ;
109 }
110
111 posix_spawn_file_actions_destroy(&actions) ;
112 posix_spawnattr_destroy(&attr) ;
113
114 #else
115 if (pipecoe(syncpipe) < 0) goto errp ;
116
117 pid = fork() ;
118 if (pid < 0) goto errsp ;
119 else if (!pid)
120 {
121 size_t len = strlen(PROG) ;
122 char name[len + 9] ;
123 memcpy(name, PROG, len) ;
124 memcpy(name + len, " (child)", 9) ;
125 PROG = name ;
126 if (n >= 2)
127 {
128 if (fd_move2(0, p[1][0], 1, p[0][1]) < 0) goto syncdie ;
129 }
130 else if (n)
131 {
132 if (fd_move(1, p[0][1]) < 0) goto syncdie ;
133 }
134 sig_blocknone() ;
135 mexec_aen(prog, argv, envp, modifs, m, 1) ;
136
137 syncdie:
138 {
139 char c = errno ;
140 fd_write(syncpipe[1], &c, 1) ;
141 }
142 _exit(127) ;
143 }
144
145 fd_close(syncpipe[1]) ;
146 {
147 char c ;
148 syncpipe[1] = fd_read(syncpipe[0], &c, 1) ;
149 if (syncpipe[1])
150 {
151 int e = c ;
152 if (syncpipe[1] < 0) e = errno ;
153 if (wait_pid(pid, &syncpipe[1]) < 0) e = errno ;
154 errno = e ;
155 goto errsp0 ;
156 }
157 }
158 fd_close(syncpipe[0]) ;
159 #endif
160
161 for (i = n ; i ; i--)
162 {
163 fd_close(p[i-1][i & 1]) ;
164 fds[i-1] = p[i-1][!(i & 1)] ;
165 }
166 return pid ;
167
168 #ifdef SKALIBS_HASPOSIXSPAWN
169 erractions:
170 posix_spawn_file_actions_destroy(&actions) ;
171 errattr:
172 posix_spawnattr_destroy(&attr) ;
173 erre:
174 errno = e ;
175 #endif
176 #ifndef SKALIBS_HASPOSIXSPAWN
177 errsp:
178 fd_close(syncpipe[1]) ;
179 errsp0:
180 fd_close(syncpipe[0]) ;
181 errp:
182 #endif
183 i = n ;
184 errpi:
185 while (i--)
186 {
187 fd_close(p[i][1]) ;
188 fd_close(p[i][0]) ;
189 }
190 return 0 ;
191 }
192